1. Field Of the Invention
The present invention relates to the cutting of fabric materials, and more particularly to a method and apparatus for cutting mesh fabric materials so as to obtain cleanly cut edges which are also true to the shape intended where cutting has taken place.
2. Background of the Invention
Present day materials used for advanced design aerospace structures must exhibit exceptional structural strength characteristics, while at the same time permit significant reduction In overall weight. One class of these materials are typically referred to as "composites", and include both organic and metal reinforced matrices.
Reinforcing materials typically used in composites are provided as fibers. Generally, the fibers consist of materials such as metals, a combination of carbon and graphite, or ceramics. These fibers may be incorporated in a matrix material as randomly arranged pieces, as an ordered arrangement of tow, as an ordered mesh arrangement including one or more layers of the fibers, or as an arrangement of continuous fibers woven in a fabric.
One of the most difficult problems faced today In the use of fabric reinforcing materials is the cutting of the material so as to achieve a cleanly cut edge true to the angular curvilinear or straight line configuration intended to be formed.
Typically, the reinforcing fibers are stiffest in one direction (e.g. in the axial direction of the fibers themselves) and the soft cross-weave fibers (e.g., materials such as molybdenum and titanium-niobium) In the some other direction. As a result, the fabric material has a tendency not to lay flat or straight, and handling causes the soft cross-weave to shift, pinch or break. When the material is cut at any angle other than parallel to the axial direction of the reinforcing fibers, these problems are multiplied and the fabric material fails to behave in a manner conducive to attaining the desired result. In fact, the fabric material, cut in such an "off-axis" direction, typically yields an uneven, jagged edge and exhibits multiple breaks in the cross-weave fibers. The more acute the angle, the greater the problem.
The current practice of using a paper cutter or of cutting the material manually with a utility knife or scissors has consistently yielded undesirable results. In addition, such conventional techniques for cutting, when applied to this type of material, are time consuming, extremely cost inefficient and impractical, especially when working with larger size pieces (e.g., over two feet in length or width).